Trimming may free up some allocatable pages that can be reused by subsequent
allocations.

This CL also fixes base::AddressRegion::contains(Address, size_t).

Bug: v8:8096
Change-Id: I3b7381fd32f7dbf186dffc1a26d5a88cd8a30d2f
Reviewed-on: https://chromium-review.googlesource.com/1249127Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56284}